Bottom Bracket Confusion

[richyrich]

I have a Trek 1.5C road bike. Still has the original crankset (FSA Vero Compact).

Last time I had it serviced at LBS (Oct 2012) I asked them to look into a creak in the bottom bracket. They replaced it (it was still the original and I'd done about 2,500 miles on it). When they removed it, there was a bit of rust discolouring on the inside of it. They replaced it with a Shimano of some description.

I am getting a similar creaking again now. It's only when out of the saddle and applying pressure to the pedals; going up a steepish climb, for example. I am wondering if it's the same problem as before so was looking into bottom brackets. However it seems very confusing over all the different types available.

I have never attempted to replace a BB before so could just take it to LBS, but would like to learn a bit more about maintaining my bike. I tried to measure the frame but it seems BBs can be 68mm or 70mm (ie 2mm difference) and it wasn't easy to measure the frame or get the tape flat to it.

I was thinking I might replace the BB with something better, but not entirely sure what will fit and if I would need to replace the chainset as well. Could I just upgrade the BB and chainset? Say I was to get an Ultegra BB and chainset. Would that be compatible with my chain, cassette etc?

How do you find out what BBs are compatible with your bike/chainset?

 

[2Loose]

The creak is unlikely to be the BB itself after such a short life, although it may be that the cranks need tightening now that they have bedded in.

Another likely cause for the creak are the pedals (amongst other things), which are easily removed to grease the threads in order to rule those out.

 

[accountantpete]

BB widths are 68mm (road) and 73mm (MTB) with 70mm on some Italian bikes.

As you have a Trek road bike it's probably a 68mm BB shell.

Also it will have English threading so the drive side is reverse threaded - you turn clockwise to loosen. The non-drive side is normal so anti-clockwise to loosen.

You will need specific tools to take the cranks and old BB off - the thread is usually so tight that the correct tool is usually required to get a proper grip.

Then you can replace the BB with an identical one (you need to find axle length and correct taper) or change the entire system.

Modern BB's have outboard bearings called Hollowtech in Shimano language. These will fit on your bike but you will need a new chainset. Personally I find these a lot better but they don't last as long.

If changing to Hollowtech I would get the LBS to do the job as they will have the tools to take the old BB off and then you can easily do any further maintenance yourself.

 

[richyrich]

The creak is unlikely to be the BB itself after such a short life, although it may be that the cranks need tightening now that they have bedded in.

Another likely cause for the creak are the pedals (amongst other things), which are easily removed to grease the threads in order to rule those out.

Thanks for the reply.

Yeah, I do wonder if it's something else rather than the BB. Is the fact it's only out of the saddle likely to point to one thing or another?

I have been unable to loosen the pedals to regrease the threads, so perhaps I ought to give this another go. They seem jammed pretty solid unfortunately. Is one of the pedals reverse threaded? I can never remember.

The crank arms are attached with an allen key type bolt, so I presume I just see if these can be tightened?

I kind of just fancied the idea of being able to change the BB myself and the ultegra BB and chainset were begging me to buy them! I could probably do without the expense at the moment though.

 

[richyrich]

BB widths are 68mm (road) and 73mm (MTB) with 70mm on some Italian bikes.

As you have a Trek road bike it's probably a 68mm BB shell.

Also it will have English threading so the drive side is reverse threaded - you turn clockwise to loosen. The non-drive side is normal so anti-clockwise to loosen.

You will need specific tools to take the cranks and old BB off - the thread is usually so tight that the correct tool is usually required to get a proper grip.

Then you can replace the BB with an identical one (you need to find axle length and correct taper) or change the entire system.

Modern BB's have outboard bearings called Hollowtech in Shimano language. These will fit on your bike but you will need a new chainset. Personally I find these a lot better but they don't last as long.

If changing to Hollowtech I would get the LBS to do the job as they will have the tools to take the old BB off and then you can easily do any further maintenance yourself.

That's great. Thanks for letting me know. I've watched a few videos on YouTube about changing BB and they always seem to have the HollowTech type which doesn't really help in explaining what type you need if you don't have HollowTech!

That does help clear things up. So, if I wanted to "upgrade" my BB, the likelihood is I would need to change the chainset as well then?

 

[rusty bearing]

Many times we've found that a creak such as described is actually down to the bolts clamping the handlebars to the stem. If dry they creak and guess what? It's when out of the saddle going up a climb and pulling on the bars. Solution is simply to remove bolts apply grease to threads and re-tighten to correct torque.
Try it before you do 'owt expensive.

 

[richyrich]

Many times we've found that a creak such as described is actually down to the bolts clamping the handlebars to the stem. If dry they creak and guess what? It's when out of the saddle going up a climb and pulling on the bars. Solution is simply to remove bolts apply grease to threads and re-tighten to correct torque.
Try it before you do 'owt expensive.

Actually, I was struggling to tell exactly where the sound was coming from. It sounded so similar to previously when I think it actually was the BB, that I assumed it was coming from that area again.

Handlebars are definitely a possibility though. I'll give that a try as well. Thanks.

 

[richyrich]

So, I've removed the stem bolts and smeared some anti-ceasing stuff on them. Re-tightened. I also finally managed to undo my pedals, with the help of a spanner and mallet. Have also applied some to the pedal threads and put those back.

The creaking seems to have gone, although gonna try out a longer ride today to see if that totally fixed it.

Thanks for your help guys. And also, at least I'll know what to do about my BB next time!

 

[richyrich]

So, only went about 25 miles today and by the end the creaking had returned.

I presume it must be either the handlebar stem clamp or the pedals as this seemed to resolve the problem. Maybe it's something else though.

Any other ideas? I'm wondering about headset. Mines still on the original. Do they wear out? What sort of life expectancy would you get from one? I notice that it has the tendency to straighten the handlebars when you make a small deviation from centre. Could this be related?

 

[rusty bearing]

That's a bit of a pain. The simple lesson here is do one thing at a time.

Head sets do wear out but I wouldn't like to say how long one should last as there are so many variables. The 'spring' in your cables will return the bars to center, if it stayed where you put it to one side or t'other I'd be worried!
It might well be in order to drop the forks and re grease at the least you will have eliminated another possibility.

I hate creaks they can be real b*****s to solve...grumble....grumble

 

[richyrich]

So, have dropped the fork and re-greased around the bearings. Also, checked and re-tightened the stem bolts. I don't think it's the headset. It all looked pretty clean and moved smoothly.

It tends to be when pulling a biggish gear from a slow speed. I tried on drops and on hoods and it seemed to be worse on hoods; so I checked them and one seemed a little loose. So they got a tighten as well!

I think it has improved, but there is still a little noise there. It's now really a matter of trying to narrow down where the noise is coming from.

Probably take it out on a longer ride tomorrow and see how I get on. The next thing I want to check is the crank arms where they attach to the BB. Unfortunately, I don't think I have an allen key big enough at the moment.

 

[betty swollocks]

Chain ring bolts tight?

 

[GrumpyGregry]

I had one mtb whose stem/bars creaked. This sorted itself out when the bars snapped.